The Action Plan for Australian Lizards and Snakes 2017

By David G. Chapple, Reid Tingley, Nicola J. Mitchell and 6 more

Lizards and snakes (squamate reptiles) are the most diverse vertebrate group in Australia, with approximately 1000 described species, representing about 10% of the global squamate diversity. Squamates are a vital part of the Australian ecosystem, but their conservation has been hindered by a lack of knowledge of their diversity, distribution, biology and key threats.

The Action Plan for Australian Lizards and Snakes 2017 provides the first comprehensive assessment of the conservation status of Australian squamates in 25 years. Conservation assessments are provided for 986 species of Australian lizards and snakes (including sea snakes). Over the past 25 years there has been a substantial increase in the number of species and families recognised within Australia. There has also been an increase in the range and magnitude of threatening processes with the potential to impact squamates. This has resulted in an increase in the proportion of the Australian squamate fauna that is considered Threatened. Notably over this period, the first known extinction (post-European settlement) of an Australian reptile species occurred – an indication of the increasingly urgent need for better knowledge and management of this fauna. Six key recommendations are presented to improve the conservation management and plight of Australian squamates.

This Action Plan represents an essential resource for research scientists, conservation biologists, conservation managers, environmental consultants, policy makers from Commonwealth and State/Territory governments, and the herpetological community.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Dec 1, 2019
• ISBN: 9781486309481

Book preview

1. Introduction

THE AUSTRALIAN SQUAMATE FAUNA AND ITS FATE

Squamate reptiles – lizards (807 species) and snakes (213 species) – are the most diverse vertebrate group in Australia and Australia is a centre of diversity for squamates, hosting 10% of the world’s species (1020 of 10 221; Uetz et al. 2018). Australia’s squamate diversity is relatively modest at higher taxonomic levels (7 of the world’s 38 lizard families, and 6 of the 26 snake families); indeed, the rich abundance of squamates in Australia is largely because of the extreme diversity of skinks (Scincidae; 458 species), which comprise 45% of the Australian squamate fauna (Cogger 2014; Wilson and Swan 2017; Uetz et al. 2018). Squamates display a fundamentally different distribution and diversity pattern to other Australian vertebrate groups (birds, mammals, frogs), with most diversity being found within the arid and semi-arid regions that span 70% of the continent, rather than the more mesic northern, south-west and eastern regions of the country (Powney et al. 2010). As nearly 96% of the squamate fauna is endemic (Webb et al. 2015), squamates represent an important part of most ecosystems, particularly in arid and semi-arid regions.

The size of the known Australian squamate fauna has grown by around 38% (738 to 1020 species) over the past 25 years. This represents an average of about 11 new species per year. The rate of new species descriptions does not appear to be abating, and if anything is increasing (see Table 3.1). This has created two key challenges for the conservation management of the Australian squamate fauna. First, it creates a ‘two-fold’ cost to attempts to assess the conservation status of squamate species: (i) a new description results in an additional species to assess the conservation status of, generally based on relatively limited knowledge of its geographic distribution, habitat and ecology, population trends and threats; and (ii) as most newly described species are split from existing species (or species complexes), the conservation status of the existing, but now re-defined, species also needs to be re-assessed. Second, recently described species generally have smaller geographic ranges than existing species and therefore are more likely to be of higher conservation concern (Meiri 2016). Both of these factors increase demands on conservation efforts and resources.

Prior to the 2017 assessments outlined in this Action Plan, researchers and conservation managers working on the conservation of Australian squamates could access only three incomplete and/or outdated sources of information:

1. The thorough, but substantially outdated, conservation assessments contained in Cogger et al. ’s (1993) The Action Plan for Australian Reptiles . This 1993 assessment used different conservation status categories and criteria to what is used today (see Section 3). In addition, 282 species have been described since 1993 and we have an improved understanding of the distribution, ecology, population trends and threats of many species that were recognised at the time.

2. The IUCN Red List assessments that were conducted for 136 Australian squamate species as part of a 2009 global process to assess random subsets of the world’s poorly-known reptile fauna (Böhm et al. 2013). Although this assessment used the current conservation status categories and criteria, only about 13% of the current squamate fauna were included in this assessment, which is the lowest percentage assessment for squamates in any region of the world (Meiri and Chapple 2016).

3. Conservation assessments done under National ( Environment Protection and Biodiversity Conservation Act 1999 [EPBC Act]) or State/Territory-based schemes. However, the national assessments encompass only a subset of threatened Australian squamates and the State/Territory-based assessments often only consider portions of the species’ entire range (see Table 2.1).

A consequence of this incomplete knowledge of the conservation status of Australian squamates is that our understanding of the threats to many species is rudimentary, or non-existent, and we have detailed knowledge of their population size or temporal trends for very few species (see Section 3). However, the threats affecting the largest numbers of squamates are the removal of native vegetation, the degradation of habitat by livestock grazing, which spans nearly 55% of the country (Webb et al. 2015), invasive predators (e.g. foxes, feral cats) and altered fire regimes (Cogger et al. 1993; Webb et al. 2015).

AIMS OF THIS ACTION PLAN

The core aim of this Action Plan is to complete a comprehensive and up-to-date review of the conservation status of all Australian squamate species. This provides a baseline from which changes in population size and status can be gauged and provides the information and recommendations necessary to inform and direct future conservation efforts. In doing so, we highlight the extraordinary diversity of, and the conservation problems faced by, the Australian squamate fauna to researchers, conservation managers and the general public. More appreciation of this fauna and its conservation challenges is fundamental to catalyse the more substantial, targeted, and effective management needed for the recovery of its threatened species.

This is the first national assessment of the Australian squamate fauna in nearly 25 years (Cogger et al. 1993). It is modelled on the The Action Plan for Australian Birds 2010 (Garnett et al. 2011; the third instalment in a decadal series) and The Action Plan for Australian Mammals 2012 (Woinarski et al. 2014). These bird and mammal action plans have played an integral role in directing the conservation management of these groups, and monitoring trends in population sizes, and in updating EPBA Act listing statuses. It is anticipated that this Action Plan will serve a similar role in the conservation of Australian lizards and snakes. The 2017 Red List assessments that form the basis for this Action Plan were completed as part of the IUCN’s Global Reptile Assessment. As Red List assessments are valid for 10 years, we strongly recommend future national assessments for squamates are also conducted at intervals of 10 years to match the IUCN’s existing assessment cycle.

Thus, the aims of The Action Plan for Australian Lizards and Snakes 2017 are to:

•provide a national overview of the conservation status of all lizard and snake species in Australian territory (terrestrial and marine) against IUCN Red List categories and criteria (IUCN 2012)

•identify the squamate species most urgently requiring conservation management attention

•determine the key threats to squamates and recommend actions to minimise those threats

•provide a baseline for assessing trends in the status of Australian lizards and snakes

•identify information gaps and recommend conservation research and management actions

•ensure that the knowledge contained in this Action Plan is incorporated into species listings under the EPBC Act and State/Territory schemes, and fast-track the listing of threatened species that are not currently listed under State/Territory and Federal legislation

•highlight those species on the cusp of becoming threatened (e.g. Near Threatened, Data Deficient species) to allow the early detection of worsening conservation status.

METHODS

Assessment of the conservation status of all Australian (including external territories) squamate species was conducted as part of the IUCN’s Global Reptile Assessment. For the minority of species whose range extends beyond Australia, their conservation status was assessed at the global level. We compiled a list of the recognised Australian terrestrial lizard and snake species using the Australian Reptile Online Database (www.arod.com.au; Macdonald 2016) as a starting point and then modified this list as per the Australian Society of Herpetologists’ official list of recognised amphibian and reptile species. During the second half of 2016, five IUCN interns compiled draft Red List accounts (e.g. population abundance, habitat and ecology, threats; as per the Guidelines for Using the IUCN Red List Categories and Criteria version 12, February 2016) for all recognised terrestrial squamate species using the published literature. Data were entered into the IUCN’s Species Information Service (SIS) database. Geographic range maps were compiled for each species from available databases (see below: Distribution Database and Mapping). Although we included some information on subspecies where relevant in the accounts, all assessments were undertaken at the level of species.

Two 5-day IUCN workshops, in Perth (February 2017; for the species whose ranges include Western Australia, and also the small set of species restricted to Christmas Island) and in Melbourne (June 2017; for the remaining species), were held to assess the conservation status of each species against IUCN Red List Criteria version 3.1 (Table 1.1). Each workshop involved coordinators, spatial analysts, IUCN facilitators and approximately 25 experts who had knowledge of the species being assessed. The draft assessments were reviewed by the workshop participants during the workshops and modified as needed. Following agreement on the supporting information by participants, the IUCN Red List Categories and Criteria were applied to each species and this was recorded in the SIS database. Post-workshop, all assessments were reviewed and accepted by the IUCN (sometimes after post-workshop revision) and published on the Red List website (www.iucnredlist.org). Assessments for the sea snake species that occur in Australian waters were provided separately by the IUCN SSC Sea Snake Specialist Group. For the 30 Australian squamate species described since these workshops (and up to August 2018), draft assessments were compiled by the taxonomists and other experts involved in the description of those new species. These draft accounts have not yet been endorsed by the IUCN and are given in Appendix 4.1.

Marine and freshwater turtles, and crocodiles were not evaluated as part of the 2017 workshops, as the IUCN had previously assessed these species via a separate process.

DISTRIBUTION DATABASE AND MAPPING

Data on Australian squamate distributions were taken from a recent distributional database maintained by the Australian Department of the Environment and Energy. This database contains occurrence records for nearly all terrestrial Australian squamate species. Development of this database involved several steps.

1. Data collation. The first step involved gathering occurrence records for all squamate species from the following sources: (i) Australian Capital Territory (ACT) Wildlife Atlas; (ii) Canberra Nature Map; (iii) the ACT subset of the Atlas of Living Australia (excluding sources that provided raw data directly, such as museums); (iv) Environment, Planning & Sustainable Development Directorate (EPSDD), ACT Government; (v) The Australian Museum; (vi) the New South Wales (NSW) subset of the Atlas of Living Australia (excluding sources that provided raw data directly, such as museums); (vii) Atlas of NSW Wildlife (BioNet); (viii) the Northern Territory (NT) subset of the Atlas of Living Australia (excluding sources that provided raw data directly, such as museums); (ix) WildNet; (x) Department of Environment, Water and Natural Resources; (xi) Tasmania Natural Values Atlas ; (xii) Victoria Biodiversity Atlas ; (xiii) Museum Victoria (only sensitive records not released to the public); (xiv) Western Australian Museum; (xv) Department of Biodiversity, Conservation and Attraction Threatened and Priority Data; (xvi) Department of Biodiversity, Conservation and Attraction Fauna Survey Data; (xvii) Online Zoological Collections of Australian Museums (OZCAM) (excluding the above sources that provided raw data); (xviii) Point records provided by Professor Shai Meiri, Tel Aviv University, Israel; and (xix) Point records provided by Professor Craig Moritz, Australian National University. For species that are not endemic to Australia, overseas records were sourced from the Global Biodiversity Information Facility (GBIF). Geographic coordinates of records from these organisations were transformed to a common datum (WGS84). Records with missing coordinates were not considered. Scientific names were reclassified so that they adhered to a consistent taxonomy.

2. Data vetting. Following data collation, the validity of records was assessed by small groups of experts at the two 2017 assessment workshops. Experts were presented with printed maps of each species’ occurrence records and the species’ range polygon from the Australian Reptile Online Database (AROD; http://www.arod.com.au ), overlaid on a base map. Experts then edited records on the maps as necessary. One dedicated analyst in each group of experts subsequently amended the AROD range polygon in real time, resulting in a refined geographic range map for each species. Only the Australian portions of a species’ range were vetted by experts.

3. Map generation. The occurrence records and revised range polygons were used to develop a map for every species. For illustrative purposes, only occurrence records that are within the species’ range polygon, or within 10 km of the outer edge of that polygon, are shown. This was done to remove spurious records (e.g. taxonomic misidentifications or when supplied coordinates were the location of a museum). Occurrence records fitting these criteria were also used to estimate the area of occupancy and extent of occurrence for each species (see below for how these were calculated).

TEMPLATE FOR ACCOUNTS FOR INDIVIDUAL TAXA

The majority of this Action Plan comprises standardised accounts of the conservation status of individual Australian squamate taxa. Full accounts are provided for the 140 species listed as Extinct, Extinct in the Wild, threatened (Critically Endangered, Endangered, Vulnerable), Near Threatened or Data Deficient. Abbreviated accounts are provided for the 846 species listed as Least Concern. The template included:

Species name. As per the Australian Society of Herpetologists official list of recognised amphibian and reptile species (referred to hereafter as the ASH species list, as at 31 August 2018).

Common name(s). We provide common names as per the ASH species list and/or Wilson and Swan (2017).

IUCN Conservation status. This provides a summary of the IUCN criteria met (or the IUCN criteria approached in the case of Near Threatened species).

Previous IUCN assessment. Where applicable, this provides an indication of any previous IUCN assessment for the species, prior to the 2017 assessment.

Justification for assigned status. This provides a detailed statement explaining the rationale for assigning the species to its IUCN Red List category.

Status under Commonwealth and State/Territory legislation. Where applicable, this section outlines the conservation status assigned to the taxon under Australian National (EPBC Act) and Australian State and Territory legislation as at August 2018. Note that the eligibility criteria (and status categories), and the process for listing and review, vary among these jurisdictions. These are summarised here.

National. Under the EPBC Act a native species is eligible for listing in one of four categories: Extinct, Critically Endangered, Endangered or Vulnerable. Assessment closely follows IUCN categories and criteria. Nominations are assessed by the Commonwealth Threatened Species Scientific Committee, which makes recommendations to the Minister responsible for the EPBC Act. Most squamate reptiles listed under the EPBC Act were transferred from the previous Endangered Species Protection Act 1992, the list of which in turn was derived from a national list adopted by the then Council of Nature Conservation Ministers. For these taxa, the listing date is given as July 2000, the date that the EPBC Act came into operation, and no listing criteria are available. Where possible and relevant, we provide some interpretation of any disparity in this status relative to the status assigned by us. Note that the EPBC Act does not provide for a Near Threatened or Data Deficient category.

Victoria. Threatened species are listed under the Flora and Fauna Guarantee Act 1988. Assessments are carried out by the Scientific Advisory Committee. Taxa are listed as ‘Threatened’ and are assessed on their status within Victoria. As well as the ‘Threatened species’ list, ‘Advisory Lists’ are maintained by the Department of Sustainability and Environment and are based on technical information and advice obtained from a range of experts. They are reviewed periodically, usually every 1–2 years. Where appropriate we include the status in the Advisory List (in brackets) in addition to the status under the Flora and Fauna Guarantee Act.

New South Wales. Threatened animal species (except fish) are listed under the Threatened Species Conservation Act 1995. Species and populations can be listed as Presumed Extinct, Critically Endangered, Endangered or Vulnerable. Assessment is modelled on IUCN categories and criteria. Listing is carried out by the New South Wales Scientific Committee and the Committee’s determinations are not subject to Ministerial review. Taxa are assessed on their status within New South Wales.

Queensland. Threatened species are listed under the Nature Conservation Act 1992. The Act categorises protected species – Extinct in the Wild, Endangered, Vulnerable, Near Threatened and Least Concern – based on trends in population size, health and distribution. Under the Act, Endangered and Vulnerable species are deemed to be ‘Threatened species’. Taxa are assessed by the Departmental Species Technical Committee using the IUCN Red List Categories and Criteria (IUCN 2012) based on status within Queensland. Northern Territory. Threatened species are listed pursuant to the Territory Parks and Wildlife Conservation Act 2000. Nominations are considered and reviews undertaken by an Expert Panel and assessment follows the IUCN categories and criteria. Draft assessments are made on status within the Northern Territory, and exhibited for public comment, before final approval from the Northern Territory Administrator. The entire list is reviewed at approximately five year intervals. Taxa may be listed as ‘Extinct’, ‘Extinct in the wild’, ‘Critically Endangered’, ‘Endangered’, ‘Vulnerable’, ‘Near Threatened’, ‘Least Concern’ or ‘Data Deficient’.

Western Australia. Threatened species are listed under the Biodiversity Conservation Act 2016.Taxa are assessed by the Western Australian Threatened Species Scientific Committee, which advises the Minister for the Environment, with listings made by the Minister. Assessment is very similar to IUCN criteria and categories. Poorly known taxa are referred to as ‘Priority’ taxa, equivalent to the IUCN Data Deficient category. These Priority taxa are allocated to one of four ranked categories (Priority 1, 2, 3 or 4) depending on the need for immediate survey, the number of known locations of occurrence, presence in lands managed for conservation and known threatening processes.

South Australia. Threatened species are listed in Schedules under the National Parks and Wildlife Act 1972. Listing is recommended by the Threatened Species Schedules Committee, within the Department of Environment, Water and Natural Resources. Schedules of the Act are lists for Endangered, Vulnerable or Rare. Extinct and Critically Endangered taxa are included in the Endangered schedule. Lists are based on status within South Australia.

Australian Capital Territory. Threatened species are listed pursuant to the Nature Conservation Act 2014. The Flora and Fauna Committee assesses taxa and advises the Minister concerning taxa that require listing. The Committee’s assessments are required to be made on nature conservation grounds only and in a regional context in accordance with specified, publicly available criteria. Taxa may be listed as Endangered or Vulnerable, based on their status with the ACT.

Tasmania. Threatened species are listed under the Threatened Species Protection Act 1995. The Scientific Advisory Committee, appointed by the Minister, is responsible for assessing taxa under publicly available guidelines. Preliminary recommendations are advertised for public comment before being forwarded to the Minister for Environment Parks and Heritage for a final decision. Taxa can be listed as Endangered (Presumed Extinct), Endangered, Vulnerable or Rare. Criteria used for assessment are similar to those in the Red List Categories and Criteria (IUCN 2012); however, ‘qualitative statements supported by expert opinion’ can also be used in the assessment process. Listing is based on status within Tasmania.

Taxonomy. Where applicable, this section summarises relevant taxonomic issues (including noting where the species is believed to represent a species complex) or provides notes about the taxonomy used.

Geographic range. This section provides a description of the distribution of the species, and includes a map of the geographic range. For most species, the map includes all occurrence records overlaid on the IUCN range polygon. For several species, however, occurrence records or IUCN range polygons were not available (the latter cases were primarily because of slight variations between the ASH taxonomy and that used in the IUCN workshops).

AOO. Provided in square kilometres (km²). Area of occupancy, calculated as per IUCN guidelines (i.e. AOO is four times the number of 2 × 2 km grid cells that contain vetted records (IUCN 2012). Note that AOO is calculated for a species’ global range.

Table 1.1.   Summary of the five criteria (A–E) used to classify a taxon to a threatened species category (from IUCN 2012).

NA = not applicable.

EOO. Provided in km². Extent of occurrence, calculated as the minimum convex polygon (MCP) of the vetted point records, as per IUCN guidelines (IUCN 2012). Calculation of a MCP requires at least five occurrence records; for species with less than five records, we report the area of the IUCN range polygon as an estimate of the EOO. Note that the EOO is calculated for a species’ global range.

Population. Summarises our knowledge of the population size of the species.

Trend. Provides information on the population trend for the species (e.g. Stable, Decreasing, Increasing).

Habitat and ecology. This section provides a brief summary of the species’ habitat preferences and ecology. In general, this section is limited to information that is relevant to conservation and management.

Habitat type table (only in the Full Accounts): summarises the habitat type and subtypes as per the IUCN’s Habitat Classification Scheme.

Threats. An outline of known and/or predicted threats to the species.

Threat table (only in the Full Accounts): summarises the threats (timing, scope, severity, impact, stresses) to the species as per the IUCN’s Threat Classification Scheme.

Conservation. A summary of other information relevant to the conservation and management of the species. As relatively little information is known about most species, and few have species-specific conservation measures, this section predominantly outlines whether the species occurs within protected areas. CITES refers to the Convention on International Trade in Endangered Species of Wild Fauna and Flora.

Assessor(s). The names of the experts who contributed to the conservation assessment for the species.

2. Conservation status assigned to all Australian lizard and snake species

Table 2.1.   This table summarises the conservation status of all recognised Australian lizard and snake species (excluding introduced species). It includes the IUCN Red List status, the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the State-based conservation status. The taxonomy follows that recognised by the Australian Society of Herpetologists and is current as at August 2018.

Status categories: EX Extinct; EW Extinct in the Wild; CR Critically Endangered; EN Endangered; VU Vulnerable; NT Near Threatened; DD Data Deficient; LC Least Concern; NE Not Evaluated; R Rare;P1 Priority One; P2 Priority Two; P3 Priority Three; P4 Priority Four; L Listed; REX Regionally Extinct; PE Presumed Extinct; *Threat-status limited to a subspecies or subpopulation. Draft relates to species described between the 2017 IUCN assessment workshops (February and June 2017) and August 2018; draft assessments have been compiled for these species, together with revised assessments for the existing species affected by the description of these new species.

National = Commonwealth EPBC Act; VIC = Victoria; AL = Advisory List; NSW = New South Wales; QLD = Queensland; WA = Western Australia; SA = South Australia; ACT = Australian Capital Territory; TAS = Tasmania; Page = page number for the species’ taxon profile.

3. Twenty-five years of change in the Australian squamate fauna

INTRODUCTION

The 2017 IUCN assessment of the conservation status of all Australian squamate species is a landmark in the understanding and management of a distinctive and large component of Australian, indeed the world’s, biodiversity. But it is the second major landmark in this area, with the notable precedent being The Action Plan for Australian Reptiles (Cogger et al. 1993), commissioned by the Australian environment department (then the Australian Nature Conservation Agency) to provide the first ever comprehensive national assessment of the conservation status of all Australian reptile species. Over a productive period of about 10 years, these Action Plans provided a series of assessments of the conservation status of Australian vertebrate groups, including birds (Garnett 1992), mammals (Lee 1995; Bannister et al. 1996; Maxwell et al. 1996; Duncan et al. 1999; Shaughnessy 1999), frogs (Tyler 1997), freshwater fish (Wager and Jackson 1993) and some invertebrate groups (Sands and New 2002). Much of the information compiled in these Action Plans formed the basis for the development of national lists of threatened species and hence the provision of some legislative protection for those species, initially through the ANZECC List of Endangered Vertebrate Fauna and the Endangered Species Protection Act 1992 and subsequently, and with more legislative clout, under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

The 25 or so years between publication of the first Action Plan for Australian Reptiles (Cogger et al. 1993) and the current publication provides an opportunity to assess changes in knowledge of that fauna and in its conservation status, and to report on the extent of management success or failure. However, there are some notable challenges in documenting and interpreting change in the conservation status of reptile species over the period spanned by these two reviews.

(1) The conservation status categories and criteria have changed over this period. Those used in the 1993 review are summarised in Table 3.1 and those used in the 2017 assessment were given in Table 1.1 . The most notable differences are that the 1993 assessment included a Rare category, but not the Critically Endangered or Near Threatened categories, and included an Insufficiently Known but not a Data Deficient category (although these are broadly similar in meaning). Furthermore, even where category names have remained constant (e.g. Vulnerable), the criteria for defining these categories have changed. Differences between the two assessments in the available menu of conservation status categories, and the way that these were defined, render it difficult to make explicit and precise comparisons between these two dates in the numbers (and proportion) of threatened reptile species.

(2) The 1993 assessment evaluated all of the then known Australian reptile species, including taxonomic components not considered in the 2017 assessment (i.e. marine and freshwater turtles, crocodiles). In the substance of this chapter, we restrict the 1993 information to squamates only.

(3) The description of the Australian squamate fauna has expanded substantially over this period (see species complement section below), with many species newly described and many taxa then considered as species either split or subsumed. This taxonomic overhaul renders it difficult to trace the change over this period in conservation status for many individual species, or comprehensively across the complement of species.

(4) The 1993 assessment included consideration of the conservation status of subspecies as well as of species, whereas the 2017 assessment was restricted to species. Although the EPBC Act allows for national listing of subspecies (or even populations) – and seven subspecies of squamates are currently (as at September 2018) listed as threatened under that Act – the focus in this chapter is on species.

Table 3.1.   Conservation status categories and definitions used in the 1993 assessment.

Note that the categories Rare and Insufficiently Known were combined in reporting of the results of the 1993 assessment (Cogger etal. 1993). Refer to Table 1.1 for status categories and criteria used in the 2017 assessment.

(5) Although still inadequate for many species, there have been major advances in knowledge of the ecology, threats, distribution, population size and trends, and management requirements for many squamate species over the period spanned by these two reviews, such that in many cases much more reliability and confidence can be ascribed to the assessment of status in 2017 than was possible for the same species in 1993. The challenge of assessing conservation status given the handicap of limited knowledge was a major concern and conclusion in the 1993 review:

‘This review has highlighted the dearth of knowledge on the distribution, biology and ecology of Australia’s reptiles’ and ‘… the knowledge base available to identify and assess the status of threatened species of reptiles in Australia is inadequate, uneven and usually fragmentary’ (Cogger et al. 1993).

However, much of the key information required for conservation status assessment for Australian squamate species, particularly of population size and its trends, still remains unknown or poorly known (Woinarski 2018).

(6) Trends in the conservation status of sets of individual species can provide a robust measure of conservation progress or decline, and such trends can be assessed consistently for many taxonomic groups using the Red List Index (Butchart et al. 2004; Butchart et al. 2006; Butchart et al. 2007; Szabo et al. 2012). However, such a quantitative and consistent index requires a current and retrospective categorisation of conservation status and the 2017 assessment did not attempt any back-casting of the conservation status of individual species. Although the 1993 Action Plan assessments were largely incorporated into national lists and legislation, they were generally not then pulled into IUCN listings. However, subsequently (in 2009), some Australian squamate species were assessed and listed for the IUCN Red List prior to the comprehensive 2017 review, mostly as part of a 2009 global process to assess random subsets of the world’s poorly known reptile fauna (Böhm et al. 2013). Here, we compare the 2009 IUCN categorisations of a subset of Australian squamates with their 2017 assessments.

(7) The description and categorisation of threats has changed between the 1993 and 2017 assessments, mostly to bring threat classes into a recently accepted global framework (Salafsky et al. 2008); this inconsistency in threat categorisation between the two reviews constrains any attempt to assess whether the relative impacts of different threats affecting threatened Australian squamates may have changed over the period spanned by these reviews.

These are formidable constraints that limit the capability to provide robust quantitative assessments of the extent to which the conservation outlook for Australia’s squamate fauna has improved or regressed over the past 25 years. However, some comparisons are still possible and these can provide some insight into conservation trends and the outlook for Australian squamates.

SPECIES COMPLEMENT

The 1993 assessment noted the then rapid advances in the taxonomic treatment of Australian squamates, highlighted by the description of many species in the years leading up to that assessment. It recognised that this taxonomic instability posed some considerable problems for the assessment of conservation status, particularly because there was little information relevant to conservation status assessment for many newly described species and because some species-complexes remained poorly resolved.

‘This task faced some difficulties … some 270 species (36% of the total reptilian fauna) have been described only during the past two decades …’ (Cogger et al. 1993).

The issue has persisted, with continuing high rates of description of new species of Australian squamates (Cogger 2014; Meiri 2016), driven partly by a renewed focus on some groups with long-recognised taxonomic challenges (e.g. blind snakes Anilios spp.), surveys in remote and previously poorly sampled areas (Oliver and Parkin 2014; Rosauer et al. 2016; Oliver et al. 2017) and the increased application of modern genetic analyses (Oliver et al. 2009; Oliver et al. 2012; Oliver et al. 2014b; Oliver et al. 2015; Laver et al. 2017). Discovery of new species continues largely at an unabated rate (Figure 3.1), with about 282 Australian squamate species newly described in the period between the 1993 and 2017 assessments. Many more species are likely to be discovered and described in the future, such that the 2017 review is also an incomplete assessment of the entire Australian squamate fauna.

Figure 3.1.   Chronology of description of Australian squamate species. Only species now recognised as valid are considered. Tallies are given in 5-year blocks (1781–85, 1786–90 etc.). Note that the final tally is for 2016 and 2017 only, rather than a 5-year period.

The 1993 review did not provide a listing of all thennamed Australian squamates or accord them all a conservation status. Rather, it focused on a subset of species that had been considered of potential conservation concern by State/Territory agencies or by experts: that subset comprised 204 reptile taxa (including 22 taxa that were not squamates). This included some species known but not then formally described. Nonetheless, the 1993 review does provide a tabulation of the total number of thenknown reptile species by family (at p. 172), indicating that 705 species of squamate were then recognised. The 2017 review assessed the status for 986 native squamate species, an increase of approximately 40% in the species complement assessed in 2017, at an average of about 11 newly described species per year over this period.

CHANGE IN CONSERVATION STATUS

For reasons noted in this chapter’s Introduction, many factors constrain an assessment of the changes in conservation status over the period spanned by the 1993 and 2017 reviews.

Nonetheless, one change is indisputable, notable and lamentable. Whereas the 1993 assessment noted that ‘no Australian reptile is known to have become extinct since 1788’ (Cogger et al. 1993), that unblemished record is no longer true. The first recognised extinction of an Australian reptile species in modern times occurred in this period. The decline of Christmas Island’s lizard fauna (of four endemic and a native but non-endemic species) was rapid (probably starting from the late 1980s: Cogger and Sadlier (1999)) and culminated in the extinction of the Christmas Island forest skink Emoia nativitatis (with the last record in the wild in 2010) (Fig. 3.2), the extinction in the wild of the blue-tailed skink Cryptoblepharus egeriae (last wild record in 2010) and Lister’s gecko Lepidodactylus listeri (last wild record in 2012), and the extirpation of the island’s population of the coastal skink Emoia atrocostata (last record in 2009) (Smith et al. 2012; Andrew et al. 2018; Oliver et al. 2018).

These losses exemplify the susceptibility of island biota to novel factors, particularly introduced species; for example, although islands smaller than Tasmania comprise less than 0.5% of Australia’s land area, species endemic to islands have comprised almost 40% of animal extinctions in Australia (Woinarski et al. 2018a). Likewise, globally, of 28 reptile species recognised as extinct by the IUCN since 1750, 26 were island endemic species.

But these losses also provide a notable lesson for conservation status assessment and listing, because the preextinction status assessments were not made or, if made, did not adequately anticipate the rapidity and severity of decline and hence the realised extinction risk. The now extinct forest skink was not assigned any conservation status in the 1993 review, was not listed as threatened under the EPBC Act until 2014 (more than 4 years after its extinction in the wild and 4 months before the last captive individual died) and was not accorded IUCN status until 2010, again after its wild population was lost. Likewise, the blue-tailed skink was not considered as a candidate threatened species in the 1993 review, was not listed as threatened under the EPBC Act until 2014 (again after its extinction in the wild) and was not accorded IUCN status until 2017 (Andrew et al. 2018).

Figure 3.2.   The first recorded post-1788 extinction of an Australian squamate occurred in the period since the landmark1993 Action Plan. The last known individual of the Christmas Island forest skink Emoia nativitatis died on 31 May 2014 (Photo: Hal Cogger).

Other changes in conservation status and outlook are more challenging to assess (Table 3.2) and need to be interpreted with due caveats. The number and proportion of Australian squamate species assessed as threatened (i.e. Critically Endangered, Endangered and Vulnerable) has increased substantially from 31 species (4.4% of all then described species) in 1993 to 67 species (6.8% of currently accepted species) in 2017. However, the 1993 tallies relate only to that assessment’s Endangered and Vulnerable categories, and the definitions then used imply that some species in the Rare or Insufficiently Known categories may also be assumed to be threatened (Table 3.1). Note that these 1993 values exclude subspecies then considered threatened, in order to render the comparison as closely-matched as possible.

The differences between the 1993 and 2017 assessments in conservation status categories used and their criteria also constrain comparison over time in the conservation status of individual species, with this comparison also constrained by some taxonomic changes (splitting and lumping) of the entity categorised in the 1993 assessment. With due regard to these caveats, Table 3.3 presents a cross-tabulation of the status assigned to individual species in both 1993 and 2017. There are several notable features of this cross-tabulation: (i) a large majority of species were considered not threatened in 1993 and still not threatened in 2017; (ii) 29 then-known species were considered not threatened in 1993, but are now considered so; (iii) 17 species considered threatened in 1993 are now considered not threatened, and (iv) the 2017 re-assessments of species considered poorly known (Rare or Insufficiently Known) in 1993 have been highly variable: most (86 species) are now considered Least Concern, but 13 are now considered threatened, six are Near Threatened and 19 remain Data Deficient.

One other perspective from which to consider changes in conservation status from 1993 to 2017 is to tally the conservation status for species recognised since 1992 and to compare the apportionment of conservation status categories for these ‘new’ species with those that are longer recognised. Such a comparison (Table 3.4) shows some marked differences: 13.7% of reptile species described since 1992 are now considered threatened (cf. 4.8% of longer-recognised species), 4.4% of the post-1992 described species are considered Near Threatened (cf. 1.4% of longer-recognised species) and 9.9% of post-1992 described species are considered Data Deficient (cf. 4.2% of the longer-recognised species). These disparities arise probably because less is known about recently described species (therefore more are categorised as Data Deficient), but also because the late discovery of many of the recently described species was because they occur in only very small areas and/or have only small population sizes, both characteristics that contribute to threatened or Near Threatened status.

Table 3.2.   The number and percentage of Australian squamate species listed as threatened in (a) the 1993 and (b) 2017 review.

As noted in the text, these numbers are not strictly comparable because of differences in categories, criteria and definitions. Note that the 1993 review listed some subspecies, but these are excluded from the tabulation here (unless all subspecies of a species were considered threatened).

Several other approaches can be used to assess the change in conservation status (or other relevant conservation parameters) of individual species over this 25-year time period. These are: (i) the population trend given in the 2017 assessments for individual species; (ii) for the relatively small number of species for which this is possible, comparison of the status assigned for species in the 2017 assessment with any previously assigned IUCN status, with this comparison generally more robust than comparisons of statuses assigned in the 1993 and 2017 assessments, because previous IUCN assessments will be based on more-or-less the same categories and criteria; and (iii) changes over time in the EPBC Act listings of individual threatened reptiles.

Table 3.5 summarises the population trends ascribed to individual species in the 2017 assessment, based generally on expert opinion. No species is considered to have an increasing population, but 62 species are considered to have decreasing population sizes. Notably, the population size is considered to be decreasing not only for most species assessed as Critically Endangered or Endangered, but also for many Near Threatened (6 of 19 such species), Least Concern (21 of 845), and Data Deficient (3 of 53) species (Table 3.5).

The 2009 assessment of a stratified random selection of Australian squamates considered 136 species (Table 3.6). Of these, 121 were accorded the same conservation status in the 2017 review and 15 were given a different status. However, all but 2 of these 15 changes are nongenuine (arising largely from the availability of more information). One of the genuine changes is for the Christmas Island species Emoia nativitatis, which was considered Critically Endangered in the 2009 assessment and Extinct in the 2017 assessment. The other change was for Furina dunmali, which was considered Vulnerable in 2009 (and previous assessments), but Data Deficient in 2017. Of course, a period of only 8 years is short and it is not unreasonable that few species would change conservation status over such a limited time period.

Other than the species ascribed IUCN conservation status in the 2009 assessment, 36 species were assessed in preceding years (mostly in 1994 or 1996), under somewhat different assessment criteria. There are five cases of likely genuine change in this set of species. The status of the Christmas Island species Lepidodactylus listeri genuinely declined from 1996, when it was assessed as Vulnerable, to Extinct in the Wild in 2017; and that of Ramphotyphlops exocoeti likewise declined from Vulnerable in the 1996 assessment to Endangered in 2017. Tympanocryptis pinguicolla is considered to have shown a marked decline in area of occupancy from 1996 (when it was assessed as Vulnerable) to 2017 (when assessed as Endangered) and comparable declines resulted in a genuine uplisting for Delma impar from Vulnerable to Endangered over the same period. In contrast, because of the establishment of a conservation reserve and threat management, Ctenotus zastictus improved in its conservation outlook, with it being delisted from Vulnerable in a 1996 assessment to Least Concern in the 2017 review.

Table 3.3.   Changes in conservation status accorded to individual species from the 1993 to the 2017 assessments.

Table 3.4.   Comparison of the conservation status assigned in 2017 for species described post-1992 and in 1992 or earlier.

Values given in body of table are numbers of species, with (in parentheses) the percentages of the column total.

Table 3.5.    Population trends given for native squamate species in the 2017 assessment: (a) relative to the ascribed reliability of that trend designation and (b) relative to assessed conservation status.

Note that these tallies exclude the single Extinct and two Extinct in the Wild species.

Table 3.6.    Changes in IUCN Red List status assigned to a stratified random subset of Australian squamates in 2009 and the same species in the 2017 IUCN assessment.

Changes over time in the conservation status of squamate species listed as threatened under the EPBC Act are summarised in Tables 3.7 and 3.8. The bulk of the currently listed species were listed at the Act’s inception, in 2000, with the lists and their status informed by the 1993 assessment (Cogger et al. 1993). The size of the list has increased, albeit very gradually over the nearly 20-year period since its original populating, with the 29 species listed in 2000 increasing to 41 in 2018. Indicative of lack of conservation progress, since the initial (2000) listing, only three species (Delma labialis, Paradelma orientalis and Nephrurus deleani) have been de-listed, with all of these cases reflecting retrospectively realised probable invalidity of the original fit to the listing criteria rather than improvement in conservation status. No species have been down-listed and only one species has been up-listed. The relative constancy in this listing probably reflects institutional inertia rather than stability in the conservation status of the squamate fauna, as the EPBC Act listing does not have a hard-wired obligation to undertake periodic and comprehensive re-assessments, but relies instead largely on opportunistic public nominations for listing or, very rarely, de-listing. However, recent uptakes of tranches of assessments from the Action Plans for birds (Garnett et al. 2011) and mammals (Woinarski et al. 2014) provide good precedents, and reasonable hope, that the assessments contained in this Action Plan will be incorporated in the national listing.

Table 3.7.   Australian squamate species listed as threatened under the EPBC Act and changes over time in this assigned status.

Species are listed by decreasing level of conservation status. Recovery plan information: date given is the year of approval for the current recovery plan and in no case has there been more than one recovery plan for a species; *joint plan for the two indicated species; **recovery plan for one species (Tympanocryptis pinguicolla), subsequently split such that the recovery plan then also encompassed actions for another species (T. condaminensis); ***species included in a regional recovery plan (for Lord Howe and Norfolk Islands) together with many other threatened species.

Only 10 of the 38 EPBC Act listed species have had recovery plans; most of these have now lapsed and there is no indication (e.g. from any down-listing) that these recovery plans have resulted in any conservation recovery.

ADVANCESIN KNOWLEDGE

In the 2017 assessment, 53 squamate species (i.e. 5.4% of all considered species) were listed as Data Deficient (Table 3.2). It is impossible to compare this level of ignorance/ uncertainty with that for the 1993 assessment, because that earlier review used different definitions and tallied together Rare and Insufficiently Known species (127 species or 18% of the then-recognised complement of species).

The IUCN assessment is based on information relating to key conservation parameters. One important parameter is population size and its trajectory. However, there was sufficient knowledge to provide an estimate of population size for very few (<10) of the squamate species assessed in 2017. Information on population trajectory was also sparse. Most assessments of population trends were of low reliability (i.e. ‘unknown’ or ‘suspected’), with the population trajectories for only six species based on observed data (Table 3.5). The population trend was considered ‘unknown’ for 354 species (36% of assessed species); where a trend was reported (as increasing, decreasing or stable), the basis of this trend ascription was mostly also ‘unknown’ or not specified (357 species) or ‘suspected’ (252 species) (Table 3.5). For only 20 species (≈ 2% of all species considered) was the basis of population trend information inferred, estimated or observed. This limited information on population trajectories for Australian squamates is consistent with a recent review that concluded there was very little direct monitoring for threatened reptile species in Australia (Woinarski 2018). The very limited amount of such population size and trend information is a constraint on the assessment of conservation status and in practice means that most of the assessment of species as threatened depends instead on the more readily determined estimates of distribution (area of occupancy and extent of occurrence), indirect measures of habitat quality and extent, and population trend information that is simply ‘suspected’.

Table 3.8.   Changes over time in the numbers of squamate species listed as threatened under the EPBC Act.

Note that this listing excludes subspecies and that the list was first populated in 2000.

THREATS

As noted in the Introduction to this chapter, the global standard for categorisation of threats has changed over the past decade or so. Nonetheless, the broad threat categories used in the 1993 assessment can generally be matched to threat categories used in the 2017 assessment. Figure 3.3 compares the frequency across species of the main threats ascribed in 1993 and 2017. There are some caveats in comparing these tallies: (i) the actual set of compared species (i.e. those listed as threatened or Rare or Insufficiently Known in 1993 and those listed as threatened, Near Threatened or Data Deficient in 2017) is different; (ii) threats were described as unknown for many species; and (iii) an increase (or decrease) in the relative ranking of threats from 1993 to 2017 is not necessarily because of increased intensity or impact, but may be influenced also by increased knowledge of the ecology of species. Broadly, the main threats described in the 1993 assessment (habitat loss, habitat degradation by livestock and feral herbivores, horticulture, introduced predators and fire) are more or less considered also the main threats to Australian squamates in 2017. Nonetheless, there are some notable changes in relative rankings. Habitat degradation by weeds is considered to affect many more species now than was the case in 1993, with most of this impact relating to habitat degradation and changes in fire intensity associated with broadscale expansion of the introduced buffel grass Cenchrus ciliaris in arid and semi-arid Australia (Schlesinger et al. 2013; McKinney et al. 2015), although responses to this factor may vary widely among reptile species (McDonald and Luke 2013; Dittmer and Bidwell 2018). From 1993 to 2017, there has also been a substantial increase in the proportion of species considered to be threatened by changed fire regimes, introduced predators, legal and illegal hunting (or take for the pet trade), poisoning by cane toads, fisheries by-catch, introduced ants, and – especially for species in alpine areas and higher elevations in the Wet Tropics – climate change.

Figure 3.3.   Tallies across species of threats to squamate species considered threatened (or Rare or Insufficiently Known) in 1993 and those considered threatened (or Data Deficient or Near Threatened) in 2017. Note that threats were not listed for some species, and that many species had several threats, so tallies across threat categories do not match the total number of species. Expanded description of threat categories: habitat loss (includes mining and urban development), livestock (habitat degradation by stock and other introduced herbivores), fire (mostly increases in fire frequency and/or intensity), introduced predators (mostly feral cats and red foxes, but also black rats), weeds (habitat degradation caused by spread of introduced plants), horticulture (crop production), climate (climate change, including increased incidence of drought), hunting (illegal and legal targeted take), tourism (tourism development and recreation), logging (timber harvesting), toads (poisoning by cane toads), fisheries (by-catch in trawling), introduced ants (habitat change and deaths caused by introduced ants, mostly crazy ants and fire ants), fragmentation (habitat fragmentation), pollution and hydrology (changed hydrology). Other threats affecting fewer than 6 species: competition from spread of introduced or native species (3 in 1993, 2 in 2017), rock removal (4, 0), habitat degradation caused by Phytophthora and other dieback (0, 2) and hybridisation (0, 1).

4. Taxon profiles

This section presents the conservation accounts for all recognised species of Australian lizards and snakes. Full accounts (~500 words each) are presented for species listed as Extinct, Extinct in the Wild, threatened (Critically Endangered, Endangered, Vulnerable), Near Threatened or Data Deficient. Abbreviated accounts (~200 words each) are provided for Least Concern species. The accounts are based on the 2017 IUCN Red List assessments for each species, with the format of each assessment consistent across taxa, as outlined in the Introduction. The profiles are arranged by squamate group (Lizards, Snakes), Family, Subfamily (if applicable) and alphabetically by scientific name.

The appendix for this section (Appendix 4.1) provides draft Red List assessments for all new species described between the two 2017 workshops (February and June) and the 31 August 2018. Where applicable, a revised assessment is provided for the existing species impacted by these taxonomic revisions. Draft assessments are also provided for the four recognised species that were Not Evaluated in the 2017 assessments.

Amphibolurus muricatus (White, 1790)

Common name: Jacky lizard

IUCN Conservation status: Least Concern

Justification for assigned status: Common and widespread, and subject to only localised threats.

Status under Commonwealth and State/Territory legislation: Rare (South Australia)

Geographic range: AOO: 10 920 EOO: 731 142

Occurs in south-eastern South Australia along the coast to northern New South Wales and south-eastern Queensland (Wilson and Swan 2013; Cogger 2014). An isolated sighting of this species in north-eastern Queensland requires confirmation.

Population: Common. Trend: Unknown

Habitat and ecology: Occurs in shrubs and other low vegetation within dry sclerophyll forests, rocky ridges and coastal heathlands. Does not occur in the alpine zone or in heavily modified environments.

Threats: Sensitive to habitat clearing caused by agricultural intensification, conversion of grazed woodlands to tilled fields and by urban expansion and associated exposure to predation by feral and domestic cats. Impacts of these threats are localised.

Conservation: Found within a variety of protected areas.

Assessor(s): Melville, J., Hutchinson, M. & Clemann, N.

Amphibolurus norrisi Witten & Coventry, 1984

Common name: Mallee tree dragon

IUCN Conservation status: Least Concern [Previous IUCN assessment: Least Concern, 2009]

Justification for assigned status: Abundant, with wide distribution and lack of significant threats across the species’ range.

Geographic range: AOO: 1156 EOO: 703 557

Occurs in southern Australia, including western Victoria and neighbouring regions of South Australia, and in the Eyre Peninsula and coastal regions of the Great Australian Bight (Cogger 2000).

Population: Has been reported as common (Robley and Wright 2003). In western Victoria, in an area where the species was previously known to be very abundant during the 1970s–1980s (Coventry 1996), surveys between 2002 and 2017 have failed to record the species and suggest a decline proceeding from the north to the south (Robertson et al. 2006; Watson 2014). Contributing factors may include a long drought during 1998–2008, large wildfires that have changed the structure of the vegetation in this region and competition with Diporiphora nobbi. Trend: Unknown

Habitat and ecology: Occurs in heath and mallee heath, and in shrubland (Clemann et al. 2005; Cogger 2000).

Threats: The main ongoing threat to the species is inappropriate fire regimes.

Conservation: The distribution of this species may fall within protected areas. Research into population trends and threats to this species is suggested to establish the spatial extent of apparent declines.

Assessor(s): Melville, J., Hutchinson, M., Clemann, N. & Robertson, P.

Chelosania brunnea Gray, 1845

Common name: Chameleon dragon IUCN Conservation status: Data Deficient

Justification for assigned status: Although it is a relatively wide-ranging species, it is rarely encountered and the population trend is unknown. Changing fire regimes and feral cats are known threats, but the extent of any declines resulting from these pressures is unknown.

Status under Commonwealth and State/Territory legislation: Near Threatened (Northern Territory)

Geographic range: AOO: 204 EOO: 710 095 Occurs widely across the Kimberly region, Western

Australia, through north-eastern Northern Territory and just across the border in north-western Queensland (Cogger 2014).

Population: There are approximately 60 museum specimens from sites around Australia; however, wild subpopulations are difficult to locate and there is no known population estimate (Trainor 2005). Trend: Unknown

Habitat and ecology: Suitable habitat includes savanna woodland and eucalypt forests; it is arboreal but usually collected on the ground or perched on debris, fallen timber or low vegetation (Trainor 2005). It is a slowmoving species, with a distinct chameleon-like action. It is known to occupy permanent territories (Trainor 2005). It can occur in disturbed and urban areas, but viability in these areas is unclear (S. Wilson pers. comm. 2017).

Threats: Feral cats are known predators of this species and late season fires could reduce population numbers (J. Melville pers. comm. 2017) and destroy its canopy habitat (Trainor 2005).

Conservation: Known to occur in a variety of protected areas (Macdonald 2016; Trainor 2005).

Assessor(s): Teale, R., Melville, J., Wilson, S. & Ellis, R.

Chlamydosaurus kingii Gray, 1825

Common name: Frilled lizard

IUCN Conservation status: Least Concern [Previous IUCN assessment: Least Concern, 2009]

Justification for assigned status: Large distribution in Australia and southern New Guinea. It is tolerant of somewhat modified habitats and present in protected areas. There are some localised threats; however, these are not thought to affect large parts of the species’ range.

Geographic range: AOO: 3232 EOO: 3 867 998

Widely distributed in Australia, the Torres Strait islands and southern New Guinea. In Australia it occurs from the Kimberley across the north of the Northern Territory to Cape York Peninsula, south to